The relationship between a simulated glaucoma impairment and postural threat on quiet stance

Peripheral visual field deficits developed through glaucoma have been shown to contribute to balance deficits and a fear of falling. Currently, there is no work that examines the relationship between fear of falling and quiet stance among glaucoma patients. Therefore, this study aimed to examine the impact of a virtual height-induced postural threat on balance control among healthy individuals exposed to a simulated glaucoma impairment. Participants stood on a force plate to measure kinetic responses while wearing a virtual reality (VR) head-mounted display (HMD) which also tracked head position. Surface electromyography (EMG) was also used to measure muscle activity from ankle stabilizing muscles. Trials were 60 s, with two at ground level and two at 7 virtual meters above ground, each exposing participants to normal vision and a VR-simulated glaucoma impairment. Electrodermal activity was collected, and questionnaires were completed following each trial to evaluate psychological aspects of the postural threat. Overall, while experiencing height-induced fear with normal vision, participants developed a tighter control of upright stance (decreased amplitude and increased frequency of balance-related movement); however, this was not observed for the simulated glaucoma conditions. Therefore, balance deficits among glaucoma patients may be mediated by fear of falling contributing to an unexpected postural strategy.